Logging mechanism for cross-organizational collaborations using Hyperledger Fabric

Organizations nowadays are largely computerized, with a mixture of internal and external services providing them with on-demand functionality. In some situations (e.g. emergency situations), cross-organizational collaboration is needed, providing external users access to internal services. Trust between partners in such a collaboration can however be an issue. Although (federated) access control policies may be in place, it is unclear which data was requested and delivered after a collaboration has finished. This may lead to disputes between participating organizations. The open-source permissioned blockchain Hyperledger Fabric is utilized to create a logging mechanism for the actions performed by the participants in such a collaboration. This paper presents the architecture needed for such a logging mechanism and provides details on its operation. A prototype was designed in order to evaluate the performance of an asynchronous logging approach. Measurements show that the proposed logging mechanism enables organizations to create a log of service interactions with limited delay imposed on the data exchange process

TimeFabric: Trusted Time for Permissioned Blockchains

As the popularity of blockchains continues to rise, blockchain platforms must be enhanced to support new application needs. In this paper, we propose one such enhancement that is essential for financial applications and online marketplaces - support for time-based logic such as verifying deadlines or expiry dates and examining a time window of recent account activity. We present a lightweight solution to reach consensus on the current time without relying on external time oracles. Our solution assigns timestamps to blocks at transaction validation time and maintains a cache reflecting the effects of recent transactions. We implement a proof-of-concept prototype, called TimeFabric, in Hyperledger Fabric, a popular permissioned blockchain platform, and experimentally demonstrate high throughput and minimal overhead (approximately 3%) of maintaining trusted time. We also demonstrate a 2x performance improvement due to the cache, compared to reconstructing account histories from the ledger